﻿// Copyright (c) .NET Foundation and contributors. All rights reserved.
// Licensed under the MIT license. See LICENSE file in the project root for full license information.

using System;
using System.Collections.Generic;
using System.Diagnostics;
using System.IO;
using System.Linq;
using System.Text;
using Mono.Linker.Tests.Extensions;
using Xunit;
#if NET
using System.Runtime.InteropServices;
using Microsoft.CodeAnalysis;
using Microsoft.CodeAnalysis.Emit;
using Microsoft.CodeAnalysis.CSharp;
#endif

namespace Mono.Linker.Tests.TestCasesRunner
{
    public class TestCaseCompiler
    {
        protected readonly TestCaseCompilationMetadataProvider _metadataProvider;
        protected readonly TestCaseSandbox _sandbox;
        protected readonly ILInputCompiler _ilCompiler;

        public TestCaseCompiler(TestCaseSandbox sandbox, TestCaseCompilationMetadataProvider metadataProvider)
            : this(sandbox, metadataProvider, new ILInputCompiler())
        {
        }

        public TestCaseCompiler(TestCaseSandbox sandbox, TestCaseCompilationMetadataProvider metadataProvider, ILInputCompiler ilCompiler)
        {
            _ilCompiler = ilCompiler;
            _sandbox = sandbox;
            _metadataProvider = metadataProvider;
        }

        public NPath CompileTestIn(NPath outputDirectory, string outputName, IEnumerable<string> sourceFiles, string[] commonReferences, string[] mainAssemblyReferences, IEnumerable<string>? defines, NPath[] resources, bool generateTargetFrameworkAttribute, string[] additionalArguments)
        {
            var originalCommonReferences = commonReferences.Select(r => r.ToNPath()).ToArray();
            var originalDefines = defines?.ToArray() ?? Array.Empty<string>();

            Prepare(outputDirectory);

            var removeFromLinkerInputAssemblies = new List<NPath>();
            var compiledReferences = CompileBeforeTestCaseAssemblies(
                outputDirectory,
                originalCommonReferences,
                originalDefines,
                removeFromLinkerInputAssemblies,
                generateTargetFrameworkAttribute)
                .ToArray();
            var allTestCaseReferences = originalCommonReferences
                .Concat(compiledReferences)
                .Concat(mainAssemblyReferences.Select(r => r.ToNPath()))
                .ToArray();

            var options = CreateOptionsForTestCase(
                outputDirectory.Combine(outputName),
                sourceFiles.Select(s => s.ToNPath()).ToArray(),
                allTestCaseReferences,
                originalDefines,
                resources,
                generateTargetFrameworkAttribute,
                additionalArguments);
            var testAssembly = CompileAssembly(options);


            // The compile after step is used by tests to mess around with the input to the illink tool.  Generally speaking, it doesn't seem like we would ever want to mess with the
            // expectations assemblies because this would undermine our ability to inspect them for expected results during ResultChecking.  The UnityLinker UnresolvedHandling tests depend on this
            // behavior of skipping the after test compile
            if (outputDirectory != _sandbox.ExpectationsDirectory)
            {
                CompileAfterTestCaseAssemblies(
                    outputDirectory,
                    originalCommonReferences,
                    originalDefines,
                    removeFromLinkerInputAssemblies,
                    generateTargetFrameworkAttribute);

                foreach (var assemblyToRemove in removeFromLinkerInputAssemblies)
                    assemblyToRemove.DeleteIfExists();
            }

            return testAssembly;
        }

        protected virtual void Prepare(NPath outputDirectory)
        {
        }

        protected virtual CompilerOptions CreateOptionsForTestCase(NPath outputPath, NPath[] sourceFiles, NPath[] references, string[] defines, NPath[] resources, bool generateTargetFrameworkAttribute, string[] additionalArguments)
        {
            return new CompilerOptions
            {
                OutputPath = outputPath,
                SourceFiles = sourceFiles,
                References = references,
                Defines = defines.Concat(_metadataProvider.GetDefines()).ToArray(),
                Resources = resources,
                AdditionalArguments = additionalArguments,
                CompilerToUse = _metadataProvider.GetCSharpCompilerToUse(),
                GenerateTargetFrameworkAttribute = generateTargetFrameworkAttribute
            };
        }

        protected virtual CompilerOptions CreateOptionsForSupportingAssembly(SetupCompileInfo setupCompileInfo, NPath outputDirectory, NPath[] sourceFiles, NPath[] references, string[] defines, NPath[] resources, bool generateTargetFrameworkAttribute)
        {
            var allDefines = defines.Concat(setupCompileInfo.Defines ?? Array.Empty<string>()).ToArray();
            var allReferences = references.Concat(setupCompileInfo.References?.Select(p => MakeSupportingAssemblyReferencePathAbsolute(outputDirectory, p)) ?? Array.Empty<NPath>()).ToArray();
            string[]? additionalArguments = setupCompileInfo.AdditionalArguments;
            return new CompilerOptions
            {
                OutputPath = outputDirectory.Combine(setupCompileInfo.OutputName),
                SourceFiles = sourceFiles,
                References = allReferences,
                Defines = allDefines,
                Resources = resources,
                AdditionalArguments = additionalArguments,
                CompilerToUse = setupCompileInfo.CompilerToUse?.ToLowerInvariant(),
                GenerateTargetFrameworkAttribute = generateTargetFrameworkAttribute
            };
        }

        private IEnumerable<NPath> CompileBeforeTestCaseAssemblies(NPath outputDirectory, NPath[] references, string[] defines, IList<NPath> removeFromLinkerInputAssemblies, bool generateTargetFrameworkAttribute)
        {
            foreach (var setupCompileInfo in _metadataProvider.GetSetupCompileAssembliesBefore())
            {
                NPath outputFolder;
                if (setupCompileInfo.OutputSubFolder == null)
                {
                    outputFolder = outputDirectory;
                }
                else
                {
                    outputFolder = outputDirectory.Combine(setupCompileInfo.OutputSubFolder);
                    Directory.CreateDirectory(outputFolder.ToString());
                }

                var options = CreateOptionsForSupportingAssembly(
                    setupCompileInfo,
                    outputFolder,
                    CollectSetupBeforeSourcesFiles(setupCompileInfo),
                    references,
                    defines,
                    CollectSetupBeforeResourcesFiles(setupCompileInfo),
                    generateTargetFrameworkAttribute);
                var output = CompileAssembly(options);

                if (setupCompileInfo.RemoveFromLinkerInput)
                    removeFromLinkerInputAssemblies.Add(output);

                if (setupCompileInfo.AddAsReference)
                    yield return output;
            }
        }

        private void CompileAfterTestCaseAssemblies(NPath outputDirectory, NPath[] references, string[] defines, IList<NPath> removeFromLinkerInputAssemblies, bool generateTargetFrameworkAttribute)
        {
            foreach (var setupCompileInfo in _metadataProvider.GetSetupCompileAssembliesAfter())
            {
                var options = CreateOptionsForSupportingAssembly(
                    setupCompileInfo,
                    outputDirectory,
                    CollectSetupAfterSourcesFiles(setupCompileInfo),
                    references,
                    defines,
                    CollectSetupAfterResourcesFiles(setupCompileInfo),
                    generateTargetFrameworkAttribute);
                var output = CompileAssembly(options);

                if (setupCompileInfo.RemoveFromLinkerInput)
                    removeFromLinkerInputAssemblies.Add(output);
            }
        }

        private NPath[] CollectSetupBeforeSourcesFiles(SetupCompileInfo info)
        {
            return CollectSourceFilesFrom(_sandbox.BeforeReferenceSourceDirectoryFor(info.OutputName));
        }

        private NPath[] CollectSetupAfterSourcesFiles(SetupCompileInfo info)
        {
            return CollectSourceFilesFrom(_sandbox.AfterReferenceSourceDirectoryFor(info.OutputName));
        }

        private NPath[] CollectSetupBeforeResourcesFiles(SetupCompileInfo info)
        {
            return _sandbox.BeforeReferenceResourceDirectoryFor(info.OutputName).Files().ToArray();
        }

        private NPath[] CollectSetupAfterResourcesFiles(SetupCompileInfo info)
        {
            return _sandbox.AfterReferenceResourceDirectoryFor(info.OutputName).Files().ToArray();
        }

        private NPath[] CollectSourceFilesFrom(NPath directory)
        {
            var sourceFiles = directory.Files("*.cs");
            if (sourceFiles.Any())
                return sourceFiles.Concat(_metadataProvider.GetCommonSourceFiles()).ToArray();

            sourceFiles = directory.Files("*.il");
            if (sourceFiles.Any())
                return sourceFiles.ToArray();

            throw new FileNotFoundException($"Didn't find any sources files in {directory}");
        }

        protected static NPath MakeSupportingAssemblyReferencePathAbsolute(NPath outputDirectory, string referenceFileName)
        {
            // Not a good idea to use a full path in a test, but maybe someone is trying to quickly test something locally
            if (Path.IsPathRooted(referenceFileName))
                return referenceFileName.ToNPath();

#if NET
            if (referenceFileName.StartsWith("System.", StringComparison.Ordinal) ||
                referenceFileName.StartsWith("Mono.", StringComparison.Ordinal) ||
                referenceFileName.StartsWith("Microsoft.", StringComparison.Ordinal) ||
                referenceFileName == "netstandard.dll")
            {

                var frameworkDir = Path.GetFullPath(Path.GetDirectoryName(typeof(object).Assembly.Location)!);
                var filePath = Path.Combine(frameworkDir, referenceFileName);

                if (File.Exists(filePath))
                    return filePath.ToNPath();
            }
#endif

            var possiblePath = outputDirectory.Combine(referenceFileName);
            if (possiblePath.FileExists())
                return possiblePath;

            return referenceFileName.ToNPath();
        }

        protected NPath CompileAssembly(CompilerOptions options)
        {
            if (options.SourceFiles.Any(path => path.ExtensionWithDot == ".cs"))
                return CompileCSharpAssembly(options);

            if (options.SourceFiles.Any(path => path.ExtensionWithDot == ".il"))
                return CompileIlAssembly(options);

            throw new NotSupportedException($"Unable to compile sources files with extension `{options.SourceFiles.First().ExtensionWithDot}`");
        }

        protected virtual NPath CompileCSharpAssemblyWithDefaultCompiler(CompilerOptions options)
        {
#if NET
            return CompileCSharpAssemblyWithRoslyn(options);
#else
            return CompileCSharpAssemblyWithCsc(options);
#endif
        }

#if NET
        protected virtual NPath CompileCSharpAssemblyWithRoslyn(CompilerOptions options)
        {
            var languageVersion = LanguageVersion.Default;
            var compilationOptions = new CSharpCompilationOptions(
                outputKind: options.OutputPath.FileName.EndsWith(".exe") ? OutputKind.ConsoleApplication : OutputKind.DynamicallyLinkedLibrary,
                assemblyIdentityComparer: DesktopAssemblyIdentityComparer.Default
            );
            // Default debug info format for the current platform.
            DebugInformationFormat debugType = RuntimeInformation.IsOSPlatform(OSPlatform.Windows) ? DebugInformationFormat.Pdb : DebugInformationFormat.PortablePdb;
            bool emitPdb = false;
            Dictionary<string, string> features = [];
            if (options.AdditionalArguments != null)
            {
                foreach (var option in options.AdditionalArguments)
                {
                    switch (option)
                    {
                        case "/unsafe":
                            compilationOptions = compilationOptions.WithAllowUnsafe(true);
                            break;
                        case "/optimize+":
                            compilationOptions = compilationOptions.WithOptimizationLevel(OptimizationLevel.Release);
                            break;
                        case "/optimize-":
                            compilationOptions = compilationOptions.WithOptimizationLevel(OptimizationLevel.Debug);
                            break;
                        case "/debug:full":
                        case "/debug:pdbonly":
                            // Use platform's default debug info. This behavior is the same as csc.
                            emitPdb = true;
                            break;
                        case "/debug:portable":
                            emitPdb = true;
                            debugType = DebugInformationFormat.PortablePdb;
                            break;
                        case "/debug:embedded":
                            emitPdb = true;
                            debugType = DebugInformationFormat.Embedded;
                            break;
                        case "/langversion:7.3":
                            languageVersion = LanguageVersion.CSharp7_3;
                            break;
                        default:
                            var splitIndex = option.IndexOf(":");
                            if (splitIndex != -1 && option[..splitIndex] == "/main")
                            {
                                var mainTypeName = option[(splitIndex + 1)..];
                                compilationOptions = compilationOptions.WithMainTypeName(mainTypeName);
                                break;
                            }
                            else if (splitIndex != -1 && option[..splitIndex] == "/features")
                            {
                                var feature = option[(splitIndex + 1)..];
                                var featureSplit = feature.IndexOf('=');
                                if (featureSplit == -1)
                                    throw new InvalidOperationException($"Argument is malformed: '{option}'");
                                features.Add(feature[..featureSplit], feature[(featureSplit + 1)..]);
                                break;
                            }
                            else if (splitIndex != -1 && option[..splitIndex] == "/nowarn")
                            {
                                var nowarn = option[(splitIndex + 1)..];
                                var withNoWarn = compilationOptions.SpecificDiagnosticOptions.SetItem(nowarn, ReportDiagnostic.Suppress);
                                compilationOptions = compilationOptions.WithSpecificDiagnosticOptions(withNoWarn);
                                break;
                            }
                            throw new NotImplementedException(option);
                    }
                }
            }
            var parseOptions = new CSharpParseOptions(preprocessorSymbols: options.Defines, languageVersion: languageVersion).WithFeatures(features);
            var emitOptions = new EmitOptions(debugInformationFormat: debugType);
            var pdbPath = (!emitPdb || debugType == DebugInformationFormat.Embedded) ? null : options.OutputPath.ChangeExtension(".pdb").ToString();

            var syntaxTrees = options.SourceFiles.Select(p =>
                CSharpSyntaxTree.ParseText(
                    text: p.ReadAllText(),
                    options: parseOptions,
                    path: p.ToString(),
                    Encoding.UTF8
                )
            ).ToList();

            if (options.GenerateTargetFrameworkAttribute)
            {
                syntaxTrees.Add(CSharpSyntaxTree.ParseText(
                    text: GenerateTargetFrameworkAttributeSource(),
                    options: parseOptions,
                    path: "AssemblyInfo.g.cs",
                    Encoding.UTF8
                ));
            }

            var compilation = CSharpCompilation.Create(
                assemblyName: options.OutputPath.FileNameWithoutExtension,
                syntaxTrees: syntaxTrees,
                references: options.References.Select(r => MetadataReference.CreateFromFile(r)),
                options: compilationOptions
            );

            var manifestResources = options.Resources.Select(r =>
            {
                var fullPath = r.ToString();
                return new ResourceDescription(
                    resourceName: Path.GetFileName(fullPath),
                    dataProvider: () => new FileStream(fullPath, FileMode.Open, FileAccess.Read, FileShare.ReadWrite),
                    isPublic: true
                );
            });

            EmitResult result;
            using (var outputStream = File.Create(options.OutputPath.ToString()))
            using (var pdbStream = pdbPath == null ? null : File.Create(pdbPath))
            {
                result = compilation.Emit(
                    peStream: outputStream,
                    pdbStream: pdbStream,
                    manifestResources: manifestResources,
                    options: emitOptions
                );
            }

            var errors = new StringBuilder();
            if (result.Success)
                return options.OutputPath;

            foreach (var diagnostic in result.Diagnostics)
                errors.AppendLine(diagnostic.ToString());
            throw new Exception("Roslyn compilation errors: " + errors);
        }
#endif

        protected virtual NPath CompileCSharpAssemblyWithCsc(CompilerOptions options)
        {
#if NET
            return CompileCSharpAssemblyWithRoslyn(options);
#else
            return CompileCSharpAssemblyWithExternalCompiler(LocateCscExecutable(), options, "/shared ");
#endif
        }

        protected virtual NPath CompileCSharpAssemblyWithMcs(CompilerOptions options)
        {
            if (Environment.OSVersion.Platform == PlatformID.Win32NT)
                CompileCSharpAssemblyWithExternalCompiler(LocateMcsExecutable(), options, string.Empty);

            return CompileCSharpAssemblyWithDefaultCompiler(options);
        }

        protected NPath CompileCSharpAssemblyWithExternalCompiler(string executable, CompilerOptions options, string compilerSpecificArguments)
        {
            var capturedOutput = new List<string>();
            var process = new Process();
            process.StartInfo.FileName = executable;
            process.StartInfo.Arguments = OptionsToCompilerCommandLineArguments(options, compilerSpecificArguments);
            process.StartInfo.UseShellExecute = false;
            process.StartInfo.CreateNoWindow = true;
            process.StartInfo.WindowStyle = ProcessWindowStyle.Hidden;
            process.StartInfo.RedirectStandardOutput = true;
            process.OutputDataReceived += (sender, args) => capturedOutput.Add(args.Data!);
            process.Start();
            process.BeginOutputReadLine();
            process.WaitForExit();

            if (process.ExitCode != 0)
                Assert.Fail($"Failed to compile assembly with csc: {options.OutputPath}\n{capturedOutput.Aggregate((buff, s) => buff + Environment.NewLine + s)}");

            return options.OutputPath;
        }

        private static string LocateMcsExecutable()
        {
            if (Environment.OSVersion.Platform == PlatformID.Win32NT)
                throw new IgnoreTestException("We don't have a universal way of locating mcs on Windows");

            return "mcs";
        }

        protected string OptionsToCompilerCommandLineArguments(CompilerOptions options, string compilerSpecificArguments)
        {
            var builder = new StringBuilder();
            if (!string.IsNullOrEmpty(compilerSpecificArguments))
                builder.Append(compilerSpecificArguments);
            builder.Append($"/out:{options.OutputPath}");
            var target = options.OutputPath.ExtensionWithDot == ".exe" ? "exe" : "library";
            builder.Append($" /target:{target}");
            if (options.Defines != null && options.Defines.Length > 0)
                builder.Append(options.Defines.Aggregate(string.Empty, (buff, arg) => $"{buff} /define:{arg}"));

            builder.Append(options.References.Aggregate(string.Empty, (buff, arg) => $"{buff} /r:{arg}"));

            if (options.Resources != null && options.Resources.Length > 0)
                builder.Append(options.Resources.Aggregate(string.Empty, (buff, arg) => $"{buff} /res:{arg}"));

            if (options.AdditionalArguments != null && options.AdditionalArguments.Length > 0)
                builder.Append(options.AdditionalArguments.Aggregate(string.Empty, (buff, arg) => $"{buff} {arg}"));

            builder.Append(options.SourceFiles.Aggregate(string.Empty, (buff, arg) => $"{buff} {arg}"));

            return builder.ToString();
        }

        protected NPath CompileCSharpAssembly(CompilerOptions options)
        {
            if (string.IsNullOrEmpty(options.CompilerToUse))
                return CompileCSharpAssemblyWithDefaultCompiler(options);

            if (options.CompilerToUse == "csc")
                return CompileCSharpAssemblyWithCsc(options);

            if (options.CompilerToUse == "mcs")
                return CompileCSharpAssemblyWithMcs(options);

            throw new ArgumentException($"Invalid compiler value `{options.CompilerToUse}`");
        }

        protected NPath CompileIlAssembly(CompilerOptions options)
        {
            return _ilCompiler.Compile(options);
        }

        private string GenerateTargetFrameworkAttributeSource()
        {
            var tfm = PathUtilities.TargetFrameworkMoniker;
            var tfmDisplayName = PathUtilities.TargetFrameworkMonikerDisplayName;
            return $"""
                [assembly: System.Runtime.Versioning.TargetFramework("{tfm}", FrameworkDisplayName = "{tfmDisplayName}")]
                """;
        }
    }
}
